Chapter 3 Flashcards

(51 cards)

1
Q

Aperture

A

size of a transducer element (for a single-element transducer) or group of elements (for an array)

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2
Q

Apodization

A

nonuniform (i.e involving different voltage amplitudes) driving of elements to an array to reduce grating lobes

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3
Q

Array

A

a transducer assembly containing several piezoelectric elements

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4
Q

Axial

A

in the direction of the transducer axis (sound travel direction)

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5
Q

Axial Resolution

A

the minimum reflector separation along the sound path that is required to produce separate echoes (i.e to distinguish between two reflectors)

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6
Q

Beam

A

region containing continuous wave sound; region through which a sound pulse propagates

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7
Q

Composite

A

combination of piezoelectric ceramic and a nonpiezoelectric polymer

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8
Q

Convex array

A

curved linear array

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9
Q

Crystal

A

element

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10
Q

Curie Point

A

temperature at which an element material loses its piezoelectric properties

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11
Q

Damping

A

material attached to the rear face of transducer element to reduce pulse duration; the process of pulse duration reduction

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12
Q

Detail resolution

A

the ability to image fine detail and to distinguish closely spaced reflectors.

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13
Q

Disk

A

a thin, flat, circular object

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14
Q

Dynamic aperture

A

aperture that increases with increasing focal length (to maintain constant focal width)

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15
Q

Dynamic focusing

A

continuously variable reception focusing that follows the increasing depth of the transmitted pulse as it travels

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16
Q

Element

A

the piezoelectric component of transducer assembly

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17
Q

Elevational resolution

A

the detail resolution in the direction perpendicular to the scan plane. it its equal to the section thickness and is the source of section thickness artifact

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18
Q

far zone

A

the region of a sound beam in which the beam diameter increases as the distance from the transducer increases; also called far field

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19
Q

focal length

A

distance from a focused transducer to the center of a focal region or to the location of the spatial peak intensity.

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20
Q

focal region

A

region of minimum beam diameter and area

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21
Q

focal zone

A

length of the focal region

22
Q

focus

A

the concentration of the sound beam into a smaller beam area that would exist otherwise

23
Q

grating lobes

A

additional weaker beams of sound traveling out in directions different from the primary beam as a result of the multi-element structure of transducer arrays

24
Q

lateral

A

perpendicular to the direction of sound travel

25
lateral resolution
minimum reflector separation perpendicular to the sound path that is required to produce separate echoes
26
lead zirconate titanate
a ceramic piezoelectric material. abb PZT.
27
lens
a curved material that focuses a sound or light beam
28
linear
adjectival form of line
29
linear array
array made of rectangular elements arranged in straight line
30
linear phased array
linear array operated by applying voltage pulses to all elements, but with small time differences (phasing) to direct ultrasound pulses out in various directions
31
linear sequenced array
linear array operated by applying voltage pulses to groups of elements sequentially.
32
matching layer
material attached to the front face of a transducer element to reduce the reflections at the transducer surface
33
natural focus
the narrowing of a sound beam that occurs with an unfocused flat transducer element
34
near zone
the region of sound beam in which the beam diameter decreases as the distance form the transducer increases; also called near field
35
operating frequency
preferred (max efficiency) frequency of operation of a transducer
36
phased array
an array that steers and focuses the beam electronically (with short time delays)
37
phased linear array
linear sequenced array with phased focusing added linear sequenced array with phased steering of pulses to produce a parallelogram- shaped display
38
piezoelectricity
conversion of pressure to electric voltage
39
probe
transducer assembly
40
resolution
the ability to distinguish echoes in terms of space, time, or strength (called detail, temporal, and contrast resolutions)
41
resonance frequency
operating frequency
42
scanhead
transducer assembly
43
sector
a geometric figure bounded by two radii and the arc of the circle included between them
44
sensitivity
ability of an imaging system to detect weak echoes
45
side lobes
weaker beams of sound traveling out from a single element in direction different form those of a primary beam
46
sound beam
the region of a medium that contains virtually all of the sound produced by a transducer
47
source
an emitter of ultrasound; transducer
48
transducer
a device that converts energy from one form to another
49
transducer assembly
transducer element with damping and matching material assembled in a case
50
ultrasound transducer
a device that converts electric energy to ultrasound energy; and vice versa
51
vector array
linear sequenced array that emits pulses from different starting points and (by phasing) in different directions.